• Journal of Korea Game Society
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• v.8 no.1
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• pp.71-77
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• 2008

The geometric structure constructs terrain from height map and non-periodically tiling with Wang tile for the detail description. It will be able to express detail bump using parallax mapping to add decal data together with height data in tile. We solve the problem when the real-time rendering and propose improving of parallax mapping for the terrain.

• Korean Journal of Remote Sensing
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• v.35 no.6_1
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• pp.895-905
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• 2019

Commercial Unmanned Aerial Vehicle (UAV) image processing software products currently used in the industry provides camera calibration information and block bundle adjustment accuracy. However, they provide mapping accuracy achievable out of input UAV images. In this paper, the quality of mapping is calculated by using orientation parameters from UAV image processing software. We apply the orientation parameters to the digital photogrammetric workstation (DPW) for verifying the reliability of the mapping quality calculated. The quality of mapping accuracy was defined as three types of accuracy: Y-parallax, relative model and absolute model accuracy. The Y-parallax is an accuracy capable of determining stereo viewing between stereo pairs. The Relative model accuracy is the relative bundle adjustment accuracy between stereo pairs on the model coordinates system. The absolute model accuracy is the bundle adjustment accuracy on the absolute coordinate system. For the experimental data, we used 723 images of GSD 5 cm obtained from the rotary wing UAV over an urban area and analyzed the accuracy of mapping quality. The quality of the relative model accuracy predicted by the proposed technique and the maximum error observed from the DPW showed precise results with less than 0.11 m. Similarly, the maximum error of the absolute model accuracy predicted by the proposed technique was less than 0.16 m.

• Journal of Korea Multimedia Society
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• v.20 no.12
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• pp.2009-2015
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• 2017

A two-dimensional lens is required to reproduce both the horizontal and vertical parallax through an autostereoscopic 3D display. Among the two-dimensional lenses, a hexagonal micro lens array (MLA) having good optical efficiency is mainly used. However, the hexagonal MLA has complex geometric features. The first feature is that the lens cells are zigzagged in the vertical direction, which should be reflected in the view number calculation for each sub-pixel. The second feature is that the four sides of a hexagonal lens cell are tilted, requiring a more careful view index assignment to the lens cell. In this paper, we propose a sub-pixel multiplexing scheme suitable for the features of the hexagonal MLA. We also propose a view-overlay algorithm based on a two-dimensional lens and compare subjective image quality with existing view-selection through autostereoscopic 3D display implementation.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.10
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• pp.777-788
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• 2006

This paper describes a displacement mapping technique which represents protruded shapes on the surface of an object. Previous approaches for image-based displacement mapping can represent only shapes depressed from the polygon surface. The proposed technique can represent shapes protruded from the underlying surface in real-time. Two auxiliary surfaces which are perpendicular to the underlying surface are added along the boundary of the polygon surface, in order to represent the pixels which overflow over the boundary of the polygon surface. The proposed approach can represent accurate silhouette of protruded shape. It can represent not only smooth displacement of protruded shape, but also abrupt displacement such as perpendicular protrusion by means of adding the supplementary texture information to the steep surface of protruded shape. By per-pixel instructions on the programmable GPU this approach can be executed in real-time. It provides an effective solution for the representation of protruded shape such as high-rise buildings on the ground.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.157-164
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• 2011

As high-resolution satellite images have enabled large scale topographic mapping and monitoring on global scale with short revisit time, agile sensor orientation, and large swath width, many countries make effort to secure the satellite image information. In Korea, KOMPSAT-2 (KOrea Multi-Purpose SATellite-2) was launched in July 28 2006 with high specification. These satellites have stereo image acquisition capability for 3D mapping and monitoring. To efficiently handle stereo images such as stereo display and monitoring, the accurate epipolar image generation process is prerequisite. However, the process was highly limited due to complexity in epipolar geometry of pushbroom sensor. Recently, the piecewise approach to generate epipolar images using RPC was developed and tested for in-track IKONOS stereo images. In this paper, the piecewise approach was tested for KOMPSAT-2 across-track stereo images to see how accurately KOMPSAT-2 epipolar images can be generated for 3D geospatial applications. In the experiment, two across-track stereo sets from three KOMPSAT-2 images of different dates were tested using RPC as the sensor model. The test results showed that one-pixel level of y-parallax was achieved for manually measured tie points.

• The Journal of Korean Association of Computer Education
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• v.8 no.1
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• pp.105-115
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• 2005

An environment model that is constructed using a single image has the problem of a blurring effect caused by the fixed resolution, and the stretching effect of the 3D model caused when information that does not exist on the image occurs due to the occlusion. This paper introduces the registration and integration method using multiple images to resolve the above problem. This method can represent parallax effect and expand the environment model to represent wide range of environment. The segmentation-based environment modeling method using multiple images can build a detail model with optimal resolution.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.4 no.2
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• pp.10-26
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• 1986

In a stereoscopic measurements on the aerial photogrammetric works, it is in general understood that the larger and the larger is a vertical scale exaggeration, the better and the better is height measuring precision. Despite the success with which a stereoscopic measurement has been applied to contour mapping as well as spot height measurement, no generally accepted theory for visual excess has yet been developed. This experiments aim at arrangement of a correlation between visual excess and height measuring precision. The stereoscopic measurements with parallax bar in the mirror stereoscope are carried out on the test model of which consists normal angle, wide angle and super wide angle respectively. With the result of this experiments, it is conclued that height measuring precision is proportional to the magnitude of visual excess.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.1
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• pp.197-210
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• 2012

The KOrea Multi-Purpose SATellite(KOMPSAT)-2 has a capability to provide a cross-track stereo imagery using two different orbits for generating various spatial information. However, in order to fully realize the potential of the KOMPSAT-2 stereo imagery in terms of mapping, various tests are necessary. The purpose of this study is to evaluate the possibility of mapping using the KOMPSAT-2 stereo imagery. For this, digital plotting was conducted based on the stereoscopic images. Also the Digital Elevation Model(DEM) and an ortho-image were generated using digital plotting results. An accuracy of digital plotting, DEM, and ortho-image were evaluated by comparing with the existing data. Consequently, we found that horizontal and vertical error of the modeling results based on the Rational Polynomial Coefficient(RPC) was less than 1.5 meters compared with the Global Positioning System(GPS) survey results. The maximum difference of vertical direction between the plotted results in this study and the existing digital map on the scale of 1/5,000 was more than 5 meters according as the topographical characteristics. Although there were some irregular parallax on the images, we realized that it was possible to interpret and plot at least seventy percent of the layer which was required the digital map on the scale of 1/5,000. Also an accuracy of DEM, which was generated based on the digital plotting, was compared with the existing LiDAR DEM. We found that the ortho-images, which were generated using the extracted DEM in this study, sufficiently satisfied with the requirement of the geometric accuracy for an ortho-image map on the scale of 1/5,000.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.4
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• pp.267-277
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• 2019

Photogrammetry and computer vision are identical in determining the three-dimensional coordinates of images taken with a camera, but the two fields are not directly compatible with each other due to differences in camera lens distortion modeling methods and camera coordinate systems. In general, data processing of drone images is performed by bundle block adjustments using computer vision-based software, and then the plotting of the image is performed by photogrammetry-based software for mapping. In this case, we are faced with the problem of converting the model of camera lens distortions into the formula used in photogrammetry. Therefore, this study described the differences between the coordinate systems and lens distortion models used in photogrammetry and computer vision, and proposed a methodology for converting them. In order to verify the conversion formula of the camera lens distortion models, first, lens distortions were added to the virtual coordinates without lens distortions by using the computer vision-based lens distortion models. Then, the distortion coefficients were determined using photogrammetry-based lens distortion models, and the lens distortions were removed from the photo coordinates and compared with the virtual coordinates without the original distortions. The results showed that the root mean square distance was good within 0.5 pixels. In addition, epipolar images were generated to determine the accuracy by applying lens distortion coefficients for photogrammetry. The calculated root mean square error of y-parallax was found to be within 0.3 pixels.